Portable power supply



FIG. 1 is a perspective view of a portable power supply, showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a rear, left, bottom side perspective view thereof.

The broken lines in the drawings depict portions of the portable power supply that form no part of the claimed design. 

CLAIM The ornamental design for a portable power supply, as shown and described. 